sb200 no/low output on 10 meters

Discussion in 'Amateur Radio Amplifiers' started by WX7G, Sep 29, 2019.

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  1. W2VW

    W2VW XML Subscriber QRZ Page

    SB-200 has zero ROHS for starters.

    Gotta go use my old reliable stuff now. Bye.
  2. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hi Steven (WB2WIK):

    It is. Fun to build as a kit, when paired with the matched KAT-500 tuner, its a great package. Can be used with CAT control to follow along with MOST rigs (understands CAT by Elecraft, Yaesu, Kenwood and Icom) and even if CAT is NOT used it will auto-sense the frequency and follow along. Rated at 500W but can easily do 600W (decent headroom compared to rating), will run 500W average power for an hour before a break is needed (which means it can run back to back QSOs on FT8, RTTY, CW, etc. all day at full power). Can also run off of a standard 120V/15A wall socket with room to spare, or 240V - its a very efficient amp.

    The Quadra is very reliable in my experience. But it is NOT idiot proof. It's main weakness is in proper power sequencing - pretty much all the failures are due to this. Otherwise its output protection, tuner, input attenuator, ability to run at half or full power, ablity to run off of 240V or 120V and autoswitch, multiple antenna and rig I/O, are excellent. It's initial setup (autotuning) is NOT quite as automatic as the KPA-500 and needs some manual help to begin with. But once set up, all is automatic. Two very large and heavy boxes, though - NOT a lighweight. I would NOT choose this amp for anything but a stationary installation.

    The Quadra "system" (separate power supply and amp) has THREE power switches, two "hard" and one "soft". They need to be thrown in a specific order. The two hard switches are on the power supply; one on the back panel where its hard to reach and one right on the front panel. The soft switch is on the amp, on the front panel, and it "remembers" if it's been thrown (on mine at least - there ARE some variations between serial numbers).

    Starting from an "all off" condition, the power supply back panel switch/circuit breaker must be turned on FIRST (and simply left on forever) followed SECOND by the front panel power supply hard switch, followed THTRD by the amp soft switch. Sequencing between the front panel hard and soft switches is important; The power supply hard switch is thrown and the user should wait until the power supply comes up and stays up for about 15 seconds - because its also powering up SOME of the amp circuitry, which includes a microprocessor, and 'settling". THEN the amp soft switch is thrown and it takes about 20 more seconds for the amp to power up, go through it's self test and be ready to go. Power down is done in the reverse order, also with pauses.

    The temptation is to simply power up/down with the power supply front panel hard power switch - and therein lies the problem. Powering the supply and amp up and down using just this switch seems to be causing the failures. This can also happen if the power in your area "blinks" off and on for 20 seconds, frequently. The failed component is almost always the inrush current limiting resistors in the soft-start circuit.

    Operators in areas with poor power reliability often connect a relay in line with the Quadra power cord to require a manual power on to prevent unwanted, unsequenced power cycling in case of short blackouts. It would have been nice if Yaesu foresaw this problem and designed around it. So power cycling sequence is this amps "Achilles heel".

    But it's a small one if you're aware of it. And if damaged, there is a lot of guidance on line as to how to fix it (no excuse, here, just that it IS user fixable).

    Brian - K6BRN
  3. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hi David (W2VW):

    Nice collection of antiques! Nothing wrong with that, or really liking the SB-200. But reliable, when much or most of the amp is 50+ years old? Not hardly. Not unless you've replaced most of the age affected components, which is nearly ALL of them. And I have friends who have. My own rebuild of a "basket case" SB-200 included replacement of all the usual parts (about 70%) including tubes. That was about 4 years ago. During that time and now, the amp has worked fine, but HAS required maintenance/fixing. Last year the meter failed and just recently one of the two "NOS" Cetrons went.

    A good friend has has the same experiences with a similar era Henry 2K Console/Classic. It's simply... age.

    Not many people want SB-200s any more, at least around here. HRO/Anaheim has had one or two sitting in their window for almost a year. Reasonably priced. There is a reason for this - common sense. Unless you love restoring and maintaining boat anchors, this is NOT the amp for you. The simple fact that it has 2,400 volts running around inside and no safety interlocks also means that it's VERY risky for a new and HV-inexperienced ham to work on.

    In the same period, my KPA-500 and Quadra have had ZERO maintenance, which is just what you'd expect from newer and much more modern equipment. They are also much more practical to frequency hop with, which I do a lot. They are "Enablers" of the way I like to operate.

    Oddly enough, my entire career has been designing, building and delivering hi-rel comms systems. Standard design-to reliability requirements are for 10, 15 and 20 years. Reliability falls off pretty rapidly after that, largely due to a variety of component calendar aging and wearout effects. And I pay on the order of 100x for components, compared to an SB-200, to ensure they are built and screened for long life/low defect rates (low FIT rates). Yet the SB-200 is 50 years old, not 10, 15 or 20.

    I suspect you know something about reliability analysis already, so already understand this.

    BTW - from the photos on your QRZ site, it looks like most of your operating station is pretty modern. So maybe your SB-200 is a "Sunday driver", just like mine?


    Brian - K6BRN
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Holy crap. Well, I never owned one and likely never will, but what a silly "not user friendly" design.

    Even my old Henry 4K Ultra (1500W out, continous coverage 3-30 MHz, 1500W steady-state RTTY rating 24/7) had ONE switch. Throw it, and a timer starts to wait for the heater to warm up, and 120 seconds later, it's good to go without any other user intervention. It switches to "operate" automatically when the tube warms up.:)

    One of the best things about tube amps is if you happen to take a lightning surge while transmitting, usually they don't care. An SS amp can either blow up, fail, or start blowing circuits if this happens.:p

    I know most "broadcast" transmitters today have transitioned to SS...this took many years but did happen, and is still happening. But those are lower-powered modules with hybrid combiners so if one module fails, you're still on the air and the next one can be plugged in. Good design, because they do fail.

    Meanwhile, my local 50kW SWBC station, just up the street from me (KVOH) runs's two old RCA 50kW BC transmitters c. 1955 or something. Lightning hits the antenna (log periodic at 180 feet) and they just keep working.:)

    For big amps, I still like tooobs although the SS amps with auto-tuning and such obviously have some great advantages, especially for contesters who change frequencies a lot and don't want to waste time tuning anything.

    Different strokes.
  5. K9STH

    K9STH Ham Member QRZ Page

    The Collins 30S-3 amplifier had automatic tuning. Unfortunately, only 3, maybe 4 (depended on which of the design team you talked with), were ever made. That amplifier used a 4CX1500A.

    W5QBM, who lived about a half-mile from me, across the golf course, had one. He was one of the Collins Radio Company sales executives who had to retire because of heart problems (we buried Joe on his 50th birthday). The auto-tune was very sensitive, it tried to follow the changes of an SSB signal! Joe modified the amplifier with a switch that would disable the auto-tune function.

    After W5QBM died, a Japanese amateur radio operator paid between $20,000.00 and $30,000.00 (only heard about the sale after it was completed) for the amplifier plus he had it air-freighted to Japan! This was in the mid 1970s.

    None of the amateur radio equipment was ever expected to still be in operation 40, 50, even 60, or more, years after it was manufactured. However, there are many examples of such equipment that is still in every day operation. Frankly, especially equipment made by Collins, Heath, and Drake, are VERY reliable and seldom have any failures. Of course, abusing the equipment is another matter.

    I work on equipment for others and less than 10% come in needing actual repairs. Most come in for alignment and preventive maintenance. That is, replacement of electrolytic capacitors, paper capacitors, etc. Although I do have a pretty large number of tubes in stock, I actually have to replace very few in the equipment. Frankly, unless abused, tubes last for many decades.

    I do have a "bit" of tube-type equipment:

    and the only unit that seems to need repair, etc., on a semi-regular basis, is my Kenwood TS-830S and it only has 3-tubes in it. So far, the tubes have never been a problem. Instead, it is things like interconnect plugs, grounds on circuit boards, and the like.

    It has been years since any of my Collins or Heath equipment has needed any maintenance. The same with the Eldico "S-Line clones" although I don't use that equipment very much.

    Tube-type equipment is not for everyone. Many amateur radio operators have to have the latest, and greatest, equipment even though most will never utilize all the "bells and whistles" that are available. Then, there are a lot people these days who should never get near anything above 13.8-volts. Unfortunately, common sense is absent in a lot of people.

    To "bad mouth" tube-type equipment based on a couple of "basket case" units is unfair. Frankly, there are definitely "modern" transceivers that are worthy of criticism.

    Glen, K9STH
    N6UH likes this.
  6. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hi Steven (WB2WIK):

    Got a smile out of that one - well said!

    Yep - the power-up/power down sequence is important on this amp. But once you get past that and it becomes a habit, all is OK. Flip on power supply, wait a few seconds, flip on amp. Done. Shutdown is the reverse.

    But you DO have to wonder what Yaesu was thinking when they built in this vulnerability. It's avoidable. Almost like the RF, Power Supply and CPU/control engineers were sitting in separate rooms with the doors nailed shut and phones disconnected, just doing their own thing and never realized how these subsystems interacted.

    Whats interesting is that failures caused by improper Pon sequencing do not happen right away - the induced damage is cumulative, so a user can think everything is just fine turning on and shutting down from just the power supply switch, and then one day, POOF! Inrush resistor fails.

    Regardless - it works GREAT for me. So does the KPA-500. As somebody said - each to their own.

    Brian - K6BRN
  7. K6BRN

    K6BRN XML Subscriber QRZ Page

    I'm certainly not "bad-mouthing" tube equipment. I've used it for years and still enjoy it. But I've also moved on - there are much better choices, now. My insanity in collecting old equipment is more focussed on clocks these days, to my XYL's dismay. But she lets me put those up on display, at least.

    The key here might be "...don't use it very much". And it's a "push". Most consumer grade electronics really has to be powered up occasionally (especially if it has tantalum caps) to have its best reliability. But startup puts strain on the components, so too many cycles reduces reliablity. And too much on-time uses up operating life - tubes in particular are consumables and don't like power cycling. In the end, 50 year old equipment is past its design life and is not terribly reliable, unless all of the vulnerable components have been replaced.

    Glad you've had good luck with yours - most likely a testament to your skill in maintaining and operating the equipment.

    BTW - when I said "Basket Case" in referring to my SB-200, I meant the condition it was in when I rebuilt it: Nearly melted 572Bs whose envelopes had sagged, blasted band switch, voltage doubler board running VERY hot and flaking into pieces, power cord that had more electrical tape on it than original insulation. I'm sure you've seen these at swap-meets. Rebuilding, testing and using it was fun and brought me back to the HW-101 days.

    Brian - K6BRN
  8. K6BRN

    K6BRN XML Subscriber QRZ Page

    Good grief! The last time I saw that much radio equipment spanning so many years, it was at the Vintage Radio and Communications Museum in Windsor Locks, CT (Not too far away fro ARRL headquarters.):

    Great group of people running it and a station you can operate yourself if you drop in with a copy of your license. I have to confess that I've bought some old tabletop tube AM receivers from them (some museum members do personal restorations - quite well) and have fun using them (and displaying them) at QTH#2 in CT. Right next to the clocks, in fact!

    Bravo on your collection! Wish I had that much room (a big basement) to do the same in.

    Best Regards,

    Brian - K6BRN
  9. K9STH

    K9STH Ham Member QRZ Page


    The Eldico equipment is not used much. However, the Collins S-Lines and Heath SB-Line equipment is a different matter. The Collins 75S-3A receiver, Collins 32S-3 transmitter, and the Henry / Tempo 2001 amplifier account for around 60% of my operation. The Heath SB-301 receiver, Heath SB-401 transmitter, and Heath SB-200 are used for around 30% of my operation. Most of the remaining operation uses either the Collins 75S-1 receiver, Collins 32S-1 transmitter, and Heath SB-200 amplifier or my Kenwood TS-830S into the Heath SB-200.

    I do have a home-brew 160-meter transverter that I now use with my Collins 75S-3A receiver and Collins 32S-3 transmitter. For 160-meters I use that transverter into a home-brew pair GI-7bT amplifier or the TS-830S into the home-brew amplifier.

    Actually, using equipment generally helps extend the life of the units. It is when things sit, without any power applied, that problems with capacitors, etc., start happening.

    Glen, K9STH
  10. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Agreed! This is an important consideration when evaluating a post on whether and how to answer it. :confused:

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